1. Field of the Invention
This invention relates to meat meal rendering apparatus. More particularly, this invention relates to a process and apparatus that facilitates highly efficient recovery of the fat content of meat meal products that normally is lost in the air stream during the rendering process.
2. Description of the Prior Art
Present meat meal rendering processes utilize high temperature cooking to remove bacteria and soften the meat, fat, bones, skin and the like. Generally, this cooking process produces a soft, pliable, dry product that contains approximately two and one-half to three percent moisture content. This dry product exits the cooking process at approximately 260.degree. Fahrenheit having a ten to fifteen percent fat content. The cooked dry product is transferred to a press such as a tapered screw conveyor where that valuable fat content is squeezed out from the rest of the meat meal through small holes. The fat is a valuable resource, generally having more value (almost twice) than the meat itself.
Older meat meal rendering plants cooled the remainder of the meat meal having the fat removed via a long screw conveyor in which the hot meat meal was exposed to ambient air. The hot meal exposed to ambient air emitting steam caused condensation to accumulate on all exposed metal surfaces and make wet accumulations in the meal producing a perfect environment for salmonella growth. The foregoing problems that existed with older meat meal rendering processes and plants created a need to develop a closed air system for cooling cooked meat meal.
The next generation of meat meal rendering equipment resulted in the design and utilization of closed cooling machines such as the Scott Cooler System manufactured by Scott Equipment Company of New Prague, Minn. These closed cooling machines generally encapsulate the hot cooked rendered meat meal in a manner which prevents exposure of the cooked meat meal to ambient air, thereby preventing loss of moisture due to evaporation and also preventing the growth of Salmonella from exposure to the ambient air. Although these closed cooling machines advanced the state of the art, the efficiency of such machines has generally been in the eight-five to ninety percent range resulting in ten to fifteen percent loss of rendered meat meal during the cooling process. The ten to fifteen percent product loss was a result of meat meal particulate matter floating in the air stream used to cool the rendered meat meal and that was usually sent to a separator, e.g. cyclone, and then onward to a scrubber prior to being released to the atmosphere. The herein above described use of closed system cooling machines have been somewhat problematic in that the meat meal particulate caused the discharged air to have an unpleasant odor. The unpleasant odor is known to have been caused by the meat meal particulate mixed with the air. As discussed herein above, the process air is generally treated or further processed with scrubbers or the like before it is released into the atmosphere. The aforesaid air treatment/processing equipment has not historically been satisfactory for treatment of air mixed with meat meal particulate since the meat meal particulate is comprised substantially of fat which tends to plug the separators or cyclones or other like air processing and treatment equipment.
The meat meal rendering process discussed herein above was further improved by running the air stream through a bag house to capture the fat particulate floating in the air stream and to further improve the efficiency of the process. However, it was discovered that the bags quickly plugged up due to oil residue on the fat particulate which rendered the bags useless. Due to the foregoing problems associated with bag houses, cyclones are typically used in modern meat meal rendering processes to capture as much of the fat particulate as possible. However, cyclones are only about ninety-five percent efficient which means that some of the fat particulate is still lost in the discharged air stream. This particulate is low ash and high protein which makes it very valuable. In view of the foregoing, it is readily apparent that a meat rendering process is needed having the capability to efficiently and effectively capture the particulate that is lost in the discharged air stream of present meat rendering processes. Also needed is an apparatus that can be added to existing meat rendering processes to improve the efficiency associated with capturing the aforesaid fat particulate.